Automatron is a 2016 downloadable expansion for Fallout 4, developed by Bethesda Game Studios and released on PlayStation 4, Xbox One, and PC. The add-on introduces a new storyline centered on a figure called the Mechanist, who has sent waves of hostile robots — including a variety called the Robobrain — loose across the Commonwealth. Players hunt down these machines and salvage components from their remains to construct and customize their own robotic companions. The modification system draws from hundreds of options, allowing combinations of limbs, armor plating, special abilities, and weapons, among them a new lightning chain gun. Cosmetic choices extend to paint schemes and voice selections, giving each companion a distinct appearance and personality. The expansion fits within Fallout 4's shooter and RPG framework, adding a crafting-focused mechanical layer alongside its new narrative content.